SAN FRANCISCO, Calif.— The Center for Biological Diversity today formally petitioned the U.S. Environmental Protection Agency (EPA) to confront the threat of ocean acidification. The petition calls upon the EPA to strengthen the water-quality standard for ocean pH and to publish guidance to help states protect U.S. waters from carbon dioxide pollution.

The oceans cover about 70 percent of the Earth’s surface and absorb about 22 million tons of carbon dioxide each day. Seawater reacts with absorbed carbon dioxide to become more acidic. This process, termed ocean acidification, has many adverse effects, including the impairment of marine organisms’ abilities to build protective shells and skeletons.

In a new report in the journal Science, scientists predict that if human sources of carbon dioxide continue to increase, ocean acidification coupled with global warming will kill the majority of the world’s coral reefs by the end of the century (Hoegh-Guldberg et al. 2007). Already, the pH of the ocean has decreased 0.1 units on average due to anthropogenic carbon dioxide. If carbon dioxide emissions continue unabated, seawater pH may decrease an additional 0.4 units — more than a 100-percent change in acidity.

According to the Center’s petition, the EPA’s current water-quality standard is outdated and woefully inadequate in the face of ocean acidification. A decline of 0.2 pH — allowed under the current standard — will be devastating to the marine ecosystem. Twenty-five leading scientists researching ocean acidification recently concluded that “a decrease of this magnitude would pose a risk to the physiology and health of a variety of marine organisms” (Caldeira et al. 2007).

“The Clean Water Act is the nation’s strongest law designed to protect water quality,” said Miyoko Sakashita, attorney for the Center for Biological Diversity’s oceans program. “Because ocean acidification is the greatest threat to the water quality of the oceans, EPA has a duty to take steps to address ocean acidification under the Clean Water Act.”

The Clean Water Act requires the EPA to update water quality criteria to reflect the latest scientific knowledge. Since the agency developed the pH standard back in 1976, an extensive body of research has developed on the impacts of carbon dioxide on the oceans. Already researchers have noted ocean acidification impacts in surface waters. Unless we take steps to dramatically reduce carbon dioxide pollution, seawater will begin to corrode the shells of shellfish, mollusks, and plankton that form the base of the marine food web.

Under the Clean Water Act, states must adopt water-quality standards at least as strong as those established by the EPA. Once adopted, these standards form a basis for regulating pollutants — in the case of ocean acidification, carbon dioxide. The Center’s petition demonstrates that protecting the oceans from acidification requires the EPA to adopt more stringent pH criteria. Additionally, it requests that the EPA provide guidance to states on how to protect ocean waters from ocean acidification and improve monitoring.

“Unless we take steps now to prevent carbon dioxide pollution, it could cause the collapse of our marine ecosystems,” said Sakashita. “It is not too late to halt ocean acidification, and EPA needs to take action immediately to address this serious water-quality threat facing our oceans.”

The Center has already petitioned ten coastal states to declare their ocean waters “impaired” under the Clean Water Act due to ocean acidification. Responses to those petitions are pending. Today’s petition marks the first step towards federal regulation of ocean acidification under the Clean Water Act.